Position switches, 3-3 Potentiometer,   3-1 Power backup, 4-29 filter,  4-26 mainframe computer, 4-27 microcomputer, 4-28 minicomputer, 4-30 requirements, 2-22 standby,   4-30 uninterruptible, 4-30 Power supplies, 4-25 components, 4-26 controlling devices, 4-26 input,  4-25 mainframe/minicomputer, 4-27 microcomputer, 4-28 output,  4-27 protection, 4-27 protection devices, 4-29 Power/temperature panels, 3-7 Printed circuit boards, 2-13 Printer interfaces, 12-5 Centronics parallel interface, 12-5 RS-232 serial interface, 12-5 Printers,  12-1 character printers, 12-9 characteristics,   12-5 control  codes,  12-3 impact printers, 12-7 nonimpact printers, 12-10 Printing character sets, 12-2 control  codes,  12-3 line characteristics, 12-4 orientation,   12-4 Procedures, boot, 5-18 mainframe computer, 8-25 microcomputer, 8-19 minicomputer, 8-22 Process data,  1-2 interrupt  handling,  5-13 Processor, I/O, 7-4 Program counter, 5-6, 5-9 Programmable interval  timers,  5-5 read-only memory, 6-30 Programs, 8-2 applications,  8-3 instructions,   8-3 mainframe computer, 8-25 microcomputer, 8-19 minicomputer, 8-22 operational,  8-3 utility,  8-3 PROM, 6-30 Protection devices,  3-2,  4-29 memory, 6-10 Protocol,  7-2 Pushbutton  switches,  3-3 Q Quantization,   13-3 Queue/stack,  interrupt,  5-13 R Random access memory (RAM), 6-3 chip,  6-20 dynamic,  6-24 static,  6-22 Read  cycle circuits,  6-20 core,  6-12 mated  film,  6-18 memory, 6-7 Read/write control,  7-20 cycle  circuits,  6-20 memories, 6-9 Read-only memory (ROM), 5-17, 6-26 Readout,  destructive,  6-2 Real-time  clock,  5-5 Receive  buffer/receive  control,  7-21 Receivers line,  7-21 transmitters, universal, 7-19 Rectifier,  4-26 Reduced  write  current,  10-28 Registers, 4-11, 5-6, 5-22 accumulator,   5-6 index,  5-6 instruction,   5-6 INDEX-11